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CHAPTER XV
CROP-ROTATIONS
The Farm Scheme.—Notwithstanding some of the theorizing that does not commend itself to the practical man, farm management is taking on the form of a science. It involves the organization of a farm for best results, and in the scheme that should be worked out for any particular farm the most important feature is the crop-rotation. The selection of crops is controlled by so many local considerations, including the personal likes and dislikes of the farmer, that very rightly the kinds of rotation are innumerable. The order in which crops may be grown with most profit is less variable, and yet even here local conditions may quickly derange the scheme of a theorist. There is, however, such right relation of facts to each other that we are getting a working philosophy, and the individual farmer can bend practice to his own liking in considerable degree, and yet not compel plants to do their part at a disadvantage. He has much liberty in the order of their growing, without endangering profits materially. Theoretically, this is not true, and the factors of production on any farm are such that the largest return is obtainable in only one scheme of farming. Practically there is rather wide liberty.
Value of Rotation.—Experience has shown the benefit of variety in crops grown on land. Among the advantages of crop-rotation are the following:
1. It enables the farmer to maintain the supply of organic matter in his soil. The roots and stubble of a grain crop are insufficient for this purpose, and the introduction of a sod or cover crop is helpful.
2. It permits the use of legumes to secure cheap supplies of nitrogen.
3. Some plants feed near the surface of the ground, and the use of other plants which send roots deeper adds to the production.
4. Some crops leave the soil in bad physical condition, and the use of other crops in the rotation serves as a corrective.
5. The keeping of livestock is made more feasible and profitable, and this leads to increase in farm manures.
6. In a proper succession of crops the soil is covered with living plants nearly all the time, and thus is prevented from washing or leaching.
7. In addition to these influences upon soil fertility, crop-rotation assists in control of insect and fungous foes and of weeds; it permits such distribution of labor on the farm that the largest total production may be secured by its employment; and it saves the farmer from sole dependence upon a single crop.
Selection of Crops.—The natural inclination of the farmer is a consideration that cannot be ignored. If a man does not like certain kinds of animals or crops, his farm or market must possess an unusual advantage to counter-balance. Illustration of this truth may be seen in every farming community.
As a rule, the crops should be those that are well adapted to the particular soils upon which they are grown. It is up-hill work to compete with producers whose soils have far better adaptation, unless the local markets equalize conditions.
The crops should follow each other in such succession that each crop naturally paves the way for the next one in the succession, or at least does not place its successor at a disadvantage.
When it is feasible, a rather large proportion of the entire produce of the rotation should be feeding-stuff for livestock, as soil fertility is most easily guarded by livestock farming. This is desirable when consistent with profit, but, as we have seen, it is not an absolute essential.
An Old Succession of Crops.—In the corn belt of the northern states some time-honored crop-rotations have been formed by corn, oats, wheat, clover, and timothy. The number of years devoted to the grain and to the sod has varied with the soil and the desire of its owner. A common succession is corn one year, oats one year, wheat one year, clover and timothy one year, timothy one year—a five years' rotation that has much substantial success behind it. Such a rotation is wholly reasonable and in accord with the nature of things. Every year furnishes some organic matter for the soil in roots and stubble, and all the produce of four years out of the five may be fed on the farm. There is one cash crop, or two if the price of the clear timothy hay justifies sale.
The manure may be hauled upon the sod when other work does not press, and it goes where the crop is one that prefers fresh manure, be that the grass or the corn. There is plenty of time after the corn to prepare for oats, and after the oats to prepare for wheat. The preparation for the wheat is sufficient for the clover and timothy. The seedings come only in the spring and the fall, when rainfall is more abundant and effective than in mid-summer. The danger of failure in case of this rotation is relatively small.
Corn Two Years.—Hunt says that the prosperity of the east, as a whole, would be greatly increased if the rotations of crops were so modified as to increase the corn acreage. He suggests the four rotations given in the table below, which is taken from Bulletin 116 of the Pennsylvania experiment station. The fertilizers recommended should maintain fertility.
CORN IN CROP-ROTATIONS
+ -+ -+ -+ -+ -+ 3 Yr. 4 Yr. 5 Yr. 7 Yr. + -+ -+ -+ -+ 1 Corn: 6 to 10 loads of manure and 25 pounds of phosphoric acid. 1 1 1 2 Corn: 6 to 10 loads of manure and 25 pounds of phosphoric acid. 2 2 3 Oats: no fertilizer. 2 3 3 4 Wheat: 50 pounds each of phosphoric acid and potash. 3 4 4 5 Clover and timothy: no fertilizer. 5 6 Timothy: 25 pounds each of nitrogen, phosphoric acid, and potash. 7 Timothy: 25 pounds each of nitrogen, phosphoric acid, and potash. + -+ -+ -+ -+ -+
The Oat Crop.—In the northern part of the corn belt the oat crop is profitable. In the southern half of Ohio and regions of like temperature the oat crop rarely pays. The heat, when the oat is in the milk stage, usually is too great. The tendency there is to eliminate this crop. Where silage is wanted, the stubble-land can be seeded directly to wheat with good results. A common practice is to seed to wheat between the shocked corn, and the wheat does poorly unless the soil is quite fertile.
Two Crops of Wheat.—A common practice has been to grow two crops of wheat, seeding first in the corn stubble-land, and plowing the ground for the second wheat crop, making a smooth surface for mowing. This method ceased to pay well when wheat became low in price. It has the advantage of giving two cash crops to the rotation.
Where winter wheat does not thrive in the north, it is dropped out, and the seeding to clover and grass is with the oat crop. There is the compensation of a large oat yield where the climate is too cold for a good crop of wheat.
The Clover and Timothy.—The timothy and clover sod is made inexpensively so far as labor is concerned. The first crop of hay is chiefly clover, and the soil is enriched by the roots and stubble, while the hay is converted into manure.
The second year the hay is nearly clear timothy. The sod should not be left until it becomes thin, but should be turned under while heavy, no matter if this must be after one season's harvest, or two. A sod stands three or four years for harvest on some farms, and without heavy fertilization there is decrease in fertility.
Two Legumes in the Rotation.—If all the crops of this five years' rotation, excepting wheat, were fed on the farm, and if all the manure were saved and rightly applied, there would be little or no difficulty in maintaining fertility, provided the soil were friendly to clover. The fact is that much such land has grown poorer, and it is known that another legume is needed in the rotation. The substitution of the soybean or cowpea for the oat crop gives excellent results. It makes a large supply of rich hay, and it fits the soil nicely for winter grain. The use of the breaking-plow is escaped. The surface of the land is in good tilth, especially if the legume was planted in rows so that cultivation could be given. A cutaway harrow, run shallow, and a roller make the seed-bed. Near the southern edge of the oat belt this substitution gives more value in the crop following corn, and at the same time conserves soil fertility.
Where land is thin, a four years' rotation of corn, soybeans or cowpeas, wheat, and clover is one of the best, because it contains two leguminous crops, and because one of them favors the wheat which follows and the clover seeded in the wheat.
Potatoes after Corn.—When potatoes are grown in the corn belt, a five years' rotation of corn, potatoes, oats, wheat, and clover, or corn, potatoes, wheat, clover, and timothy, is one of the best. When a late potato crop is grown, there is not time for seeding to wheat in cool latitudes, and the oat crop, or the soybean, fits in best. Farther south, where the oat crop is less profitable, there usually is time to go directly to wheat.
The advantage in this rotation is that the fresh manure can be used on the sod for the corn, and the potato thrives in the rotted remains of the sod and manure. Corn leaves the soil in good physical condition for the potato. Commercial fertilizer is used freely for the potato, which repays fertilization in higher degree than most other staple crops. The land can be prepared for seeding to wheat and grass with a minimum amount of labor. The rotation is excellent where there is enough fertility for the potato, which usually can be by far the most profitable crop in the entire rotation.
A Three Years' Rotation.—Farm conditions may require that certain fields in the farm go under a crop-rotation covering three years. In the winter wheat belt this may be clover, corn, and wheat, or clover, potatoes, and wheat. It is an excellent rotation when early planted potatoes or silage corn follows the sod, favoring the wheat in which the clover again is seeded. The ground is plowed only once in three years. The clover furnishes hay for the farm, and organic matter with nitrogen for the land. There are two cash crops in the rotation when potatoes are grown, and that makes a heavy draft upon fertility. Experience has demonstrated that commercial fertilizers or manure become necessary as a supplement to clover in a three years' rotation embracing potatoes. This rotation gives good control of most weeds and insect enemies.
Where wheat is unprofitable, the oat crop is used in its stead. If mixed hay is wanted, timothy is sown with the clover. This is poor practice from the standpoint of soil fertility because the draft upon humus is heavy in a close rotation embracing a tilled crop and small grain. The sod should be chiefly clover, or manure should be used in connection with commercial fertilizer.
Grain and Clover.—In the case of some soils it is possible to grow a wheat or corn crop each year, clover being grown as a catch crop. In the long run, this practice will fail because the clover will cease to make a thrifty growth when grown so nearly continuously. It succeeds best on fertile land.
Potatoes and Crimson Clover.—In some potato-producing sections in warm latitudes it is a not uncommon practice to grow potatoes year after year on the same land, seeding to crimson clover after the removal of the crop in August, and plowing the clover down early in the spring. Rye has been similarly used farther north. In each instance available plant-food must be freely supplied. The practice is a temporary expedient of value, but probably cannot be pursued indefinitely with profit. This is likewise true of similar close rotations.
CHAPTER XVI
THE NEED OF COMMERCIAL FERTILIZERS
Loss of Plant-food.—The soil is composed chiefly of material that never will enter into the structure of plants, but that serves us by affording a congenial place for plant-roots. It anchors the plants, holds moisture for them, and offers opportunity for all the processes necessary to the preparation of plant-food and to its use. In this material are the abundant supplies of such plant-food as silica, but, as has been previously stated, their very abundance leads us rightly to disregard them in our thinking. Our interest is only in the very small percentage of material that is composed of the four constituents which may be lacking in available form in the soil: nitrogen, phosphoric acid, potash, and lime. We believe that the only consideration that now need be given lime is as a soil-corrective and, when there is no acidity, we may assume that there is plenty of lime present. When yields of crops tend to decrease, the only plant-foods with which we are concerned are nitrogen, phosphoric acid, and potash.
The materials were stored in all agricultural land, and much of the supply is in inert forms. They help to make what we call the natural strength of the land. The rotting of organic matter, tillage, and many other agencies bring about some availability. The removal of crops, leaching, etc., reduce the supply. The right use of commercial fertilizers involves the addition of some plant-food when the available supply in a particular soil is inadequate.
Prejudice against Commercial Fertilizers.—The owner of land that was made very fertile by nature, and that has not been cropped long enough to reduce the supply of available fertility to the danger-point, rarely fails to entertain a prejudice against commercial fertilizers. It is the rule that he refuses to consider their use until the decrease in crop yields becomes so serious that necessity drives. If his land is not contributing its fair share of grain, vegetables, etc., to the markets, but has all its products converted into meat or milk, the supply of available plant-food may remain sufficient for so long a time that the matter cannot have any interest for him. If the land is producing some crops for market, there is reduction in its mineral store. It is the rule that the boundary of profitable use of commercial fertilizers pushes westward from the older and naturally poorer seaboard states about one generation after need shows in the crop yields. Lack of knowledge, the association of the use of commercial fertilizers with poor land, and some observation of the unwise use of fertilizers, combine to create a lively prejudice. They are viewed as stimulants only, and costly ones at that.
Are Fertilizers Stimulants?—Some words carry with them their own popular condemnation. We are accustomed to draw a sharp line between foods and stimulants, and to condemn the latter. To stimulate is to rouse to activity. Tillage does not add one pound of plant-food to the soil, and its office is to enable plants to draw material out of the soil. It makes activities possible that convert soil material into crops. Fertilizers add plant-food directly to the soil, and it is also to their credit that their judicious use favors increased availability in some of the compounds already in the soil. The greater part of the labor put on land is designed to make plant-food available, either by providing moisture, or ease of penetration of plant-roots, or activity of bacteria, or other means that will permit plants to remove what they need for growth. Fertilizers supply fertility directly and indirectly, but it is their direct service in meeting a deficiency in plant-food that affords all needed justification for their use by practical farmers.
Referring to the thirty years' soil fertility experiments of the Pennsylvania station, Hunt says that they "show that there is nothing injurious about commercial fertilizers. For thirty years certain plats in this experiment have received no stable manures. No organic matter has been added to the soil except that which was furnished by the roots and stubble of plants grown. These plats are not only as fertile as they were thirty years ago, but they have yielded, and continue to yield, as good crops as adjacent plats which have received yard manure every two years in place of commercial fertilizer."
Soil Analysis.—There is wide misconception regarding the value of chemical analysis of the soil as an aid in making choice of a fertilizer. Analysis has shown that some soil types are relatively richer in plant-constituents than are others, and it has shown abnormal deficiency in some types of limited area. It has given us more knowledge of soils, but as a guide to fertilization in particular instances it usually has no value. The samples used by an analyst are so small that the inaccuracy in his determination may easily be greater than the total amount of plant-food in a very heavy application of commercial fertilizer. A field that has been reduced to temporarily low productive power by heavy cropping or bad farming methods may show a greater content of plant-food than another field that is in a highly productive condition. This is a fact difficult of acceptance by some who want the aid of science, but such are the present limitations. The weight of a fertilizer application is so small in comparison with the weight of the surface part of an acre of land that the use of a ton of fertilizer may not be detected in the analyst's determinations, and moreover his determinations of actual availability in the soil's supplies are not serviceable in the selection of a fertilizer for any particular field and crop.
Physical Analysis.—Chemical analysis is costly and unsatisfactory as a guide to fertilization. Physical analysis by a competent man may have distinct value, and especially to one lacking experience with his soil. The mapping of soils by national and state authorities has given pretty accurate knowledge of hundreds of soil types, their location and characteristics, and when a soil expert obtains a sample of soil and the history of its past treatment, he can assign it to its type and give to its owner dependable advice regarding its crop-adaptation and probable fertilizer requirements.
The Use of Nitrogen.—There is no fully satisfactory way of determining the kind and amount of fertilizer that should be used at any particular time for any one crop. Perfection in this respect is no easier in attainment than in other matters. There are, however, means of arriving at conclusions that are a valuable guide.
In a general way, nitrogen is in scant supply in all worn soils. Wherever the cropping has been hard, and manure has not gone back to the land, the growth in stalk and leaves of the plant is deficient. The color is light. Inability of a soil to produce a strong growth of corn, a large amount of straw, or a heavy hay crop, is indicative of lack of nitrogen in nearly every instance.
The legumes, such as clover, and the stable manures are rich in nitrogen, and when the scheme of farming involves their use on all the land of the farm, no need of purchased nitrogen may arise in the production of staple crops. In the black corn soils the nitrogen content originally was high.
Lands that naturally are not very fertile rarely have enough available nitrogen. Where timothy is a leading crop, the demand for nitrogen is heavy. A cold spring or summer, checking nature's processes in the soil, may cause a temporary deficiency in available nitrogen in land that usually has a sufficient supply. Associating a rank growth of stalk and leaf with an abundance of nitrogen, the experienced man can form a pretty safe opinion regarding the probable profitableness of an investment in this element. It costs nearly four times as much per pound as either of the two other constituents of a fertilizer, and so far as is feasible it should be obtained through the legumes and stable manure.
Phosphoric-acid Requirements.—Soil analyses show that the content of phosphoric acid in most soils of this country is relatively small. The results of experiments with the various constituents of fertilizers are in accord with this fact. Fertilizer experiments at the various stations and on farms are nearly a unit in showing that if any need in plant-food exists, phosphoric acid is deficient. When crop-producing power decreases, and the farmer begins to seek a commercial fertilizer to repair the loss, he finds that bone-dust or acid phosphate is serviceable. The resulting increase in yield often leads to such sole dependence upon this fertilizer that clover and manure are disregarded, the percentage of humus is allowed to drop, and finally the fertilizer is brought into disrepute. The need of phosphoric acid is so common that it is the sole plant-food in much fertilizer, and the dominant element in practically all the remainder on the market.
The Need of Potash.—Land which is deficient in organic matter ordinarily is lacking in available potash, and responds with profit to applications, provided the nitrogen and phosphoric-acid requirements have been met. Clay soils contain far more potash than sandy soils, and in a farming scheme for them that permits the use of manure and clover, it may not become necessary to buy much potash. The liberal use of straw in the stables, and the saving of all the liquid manure, are helps. Farms from which the hay and straw have been sold for a long period of time develop an urgent need of potash. Much muck land is very deficient in this constituent.
Fertilizer Tests.—Every farmer should conduct some fertilizer tests for himself. It is only the soil itself that can make an adequate reply to a question regarding its needs. The test should be made under conditions furnishing evenness in the soil, and it should be continued for years. There is pleasure to an intelligent farmer in such questioning of his soil, and only in this way can assurance be obtained that the investment in fertilizers is the wisest that can be planned for the farm.
There are only three plant constituents to be tested, but they must be used in combination as well as singly. A soil that is deficient in the three may not give any return from potash alone, and usually does not, although it may give a marked increase from use of phosphoric acid alone. The plats may be eight rods long and one rod wide, containing each one twentieth of an acre, and having strips two feet wide separating them. The following chart suggests quantities of fertilizers to be used on the one-twentieth acre plats, 10 in number:
- Nothing. - 5 pounds nitrate of soda. - 18 pounds 14 per cent acid phosphate. - 4 pounds muriate of potash. - Nothing. - 5 pounds nitrate of soda. 18 pounds 14 per cent acid phosphate. - 5 pounds nitrate of soda. 4 pounds muriate of potash. - 18 pounds 14 per cent acid phosphate. 4 pounds muriate of potash. - 5 pounds nitrate of soda. 18 pounds 14 per cent acid phosphate. 4 pounds muriate of potash. - Nothing. -
Variation in Soil.—The difficulty in determining the character of fertilizer for a field, due to variation in the soil, is overestimated. Very often a land-owner says, "I have a dozen kinds of soil in every field." This is true in a way, it may be, but if all the field has had the same treatment in the past, the probability is that the fertilizer which is best for one part of the field will be quite good for the other parts. The likeness in characteristics that permits the land to be cropped as one field gives some assurance of likeness in plant-food needs, even where the proportion of clay and sand varies and the color is not the same.
There may be wide variation in the productive power of the fields of a farm, due to the treatments they have received. The land that grows heavy clover in a close rotation, or receives all the stable manure, may need neither nitrogen nor potash, while another field, hard-run by timothy and corn, may need a complete fertilizer. When a careful fertilizer test on land of only average productive power has been made, the owner has some definite knowledge of his soil that enables him to give more intelligent treatment to all his fields than was possible before the test had been made. He observes the appearance and yield of plants where the plant-food requirement was fully met, and makes allowance in other fields for gains or losses in the soil due to different treatment. It is out of the question to become discouraged before a beginning has been made. If yields are limited by absence of plant-food, fertilizers must be used. If money must be expended for fertilizers, it is only good business to know that the money is expended to the best advantage.
CHAPTER XVII
COMMERCIAL SOURCES OF PLANT-FOOD
Acquaintance with Terms.—The hesitation of many users of commercial fertilizer to master the few technical terms used in analyses of the goods, for which over one hundred million dollars annually are expended in this country, is to be deplored. The number of the materials available for any large use as sources of plant-food in a commercial fertilizer is small, and something of their characteristics should be known. Every farmer should have a working knowledge of these materials—their sources, the percentage of plant-food carried by them, and their probable availability. He should know in a general way their advantages and disadvantages in comparison with each other.
Nitrate of Soda.—One of the best carriers of nitrogen is nitrate of soda, which is imported from Chili, South America, where great beds exist. The most of the impurities are removed, and the nitrate of soda comes to us in bags holding 200 pounds, and looks much like discolored salt. It is easily soluble in water, and usually contains a little over 15 per cent of nitrogen, which is in a very available form. Its immediate availability brings it into use by gardeners and truckers, and it is an excellent source of nitrogen for grass fertilizers to be used in the early spring. It was formerly advised that nitrate of soda should not form part of a fertilizer for use before plant-roots had filled the ground, its high availability being supposed to lead to heavy loss by leaching. The Pennsylvania experiment station uses it as its sole source of nitrogen in fertilizers for staple crops on its 900 acres of farm land. It is effective in fertilizers for corn, wheat, potatoes, and grass, as well as for special crops.
The warnings regarding loss by leaching should not be disregarded, however. If the price of nitrogen in an organic form were as low as it has been in nitrate of soda, and if the soils of the Pennsylvania station farms were sandy, the use of nitrate of soda as the sole carrier of nitrogen would be inadvisable. The only fact of consequence is that the danger of loss has been over-stated, turning some farmers away from the use of a good and relatively cheap carrier of nitrogen.
Sulphate of Ammonia.—This is a by-product in the manufacture of coke and also of illuminating gas. Hunt estimates that the amount of nitrogen lost annually in Pennsylvania's coke industry would be sufficient, if recovered by proper type of ovens, to furnish every acre of land under cultivation in the state with four fifths of all the nitrogen needed to keep it in a maximum state of fertility.
Sulphate of ammonia contains about 20 per cent of nitrogen, which is in a quite available form. It has a tendency to exhaust the lime in the soil, producing an acid condition. Some plats in the fertilizer experiment at the Pennsylvania station have received their nitrogen in the form of sulphate of ammonia for 30 years, and are now in such acid condition that no crops thrive upon them. The corrective, of course, is lime, and if ammonium sulphate were somewhat lower in price, its use would be profitable, justifying cost of correction of acidity if it should occur. It is used by manufacturers of commercial fertilizers, and is well adapted to mixtures on account of its physical condition.
Dried Blood.—There is no more satisfactory source of organic nitrogen than dried blood of high grade. The best blood, red in color, contains nearly as much nitrogen as nitrate of soda, running from 13 to 15 per cent. The nitrogen is not as quickly available as that in the nitrate, but is more so than that in any other form of organic nitrogen. One would rarely go amiss in the purchase of dried blood as a carrier of nitrogen if the price were relatively as low as in the case of nitrate of soda, but he should not let any prejudice in favor of animal origin of fertilizers lead him to pay an excessive price per pound for the nitrogen contained in it. Such a prejudice has caused the nitrogen in a good red blood to sell for one half more per pound than in nitrate of soda, and it is not a good purchase on that basis.
The lower grades of dried blood on the market contain as low as 6 per cent of nitrogen, and the animal refuse put into it gives it a content of a few per cent of phosphoric acid. This black blood is very variable in composition, and should always be accompanied by a guaranteed analysis.
Tankage.—The waste from the slaughter of animals goes into a product called tankage. The refuse is cooked for removal of the fat, and then ground. It may run high in nitrogen on account of the amount of meat in the mixture, and it may be low in nitrogen and very high in phosphoric acid by reason of the large amount of bone in the mixture. Only a guarantee of analysis affords safety to the buyer. It is a relatively slow and good fertilizer, and is used usually in connection with forms of plant-food that are more quickly available.
Fish.—Near the Atlantic coast a large quantity of ground fish, after the extraction of oil, is used as a fertilizer, but the cost of the nitrogen and phosphoric acid in this carrier is relatively too high to justify its free use. Like dried blood, its organic character gains for it a popularity that does not have full justification in fact.
Animal Bone.—The original source of phosphoric acid as a fertilizer was animal bone, just as hard-wood, unleached ashes were the source of potash. The organic character of the animal bone made it appear more truly a manure than could any rock or other inorganic substance. There is no more satisfactory source of phosphoric acid than animal bone, and if it were in full supply for the needs of soils, there would be little occasion to discuss the merits of rock-phosphate and other similar materials. The supply is a small fraction of the need. If all animal bone were carefully saved and returned to the land that produced all of our animals, it would return to the soil only what those animals carried away in their bones, and that is indeed a small fraction of all the draft our crops make upon the soil's supply of this one substance. Some of the best animal bone goes into the manufacture of articles that never contribute anything to the soil, and there are other sources of loss. The supply of phosphoric acid from bone is too small, when compared with the land's need, to deserve more than a small fraction of the consideration it receives by users of commercial fertilizers.
The peculiar situation respecting animal bone has come about through a form of deceit. The demand for bone existed, and there was no legal restraint in the matter of branding phosphatic rock as "bone," "bone-phosphate," etc. In the past, nearly all forms of rock-phosphates have carried the word "bone" on the bag to quiet the apprehension of those who entertained a prejudice against anything other than animal bone. Nearly all the phosphoric acid has come from rock, and its use has been necessary and profitable, but the misrepresentation fostered the old-time prejudice. Within recent years some manufacturers have tired of the seeming deceit that served no purpose with many customers, and have placed acid phosphate and mixed goods upon the market without the intimation that the phosphoric acid was derived from animal bone.
The demand for bone makes prices high for the very limited amount upon the market, when availability is taken into account, and the advice that such goods be used would be valueless if it had any general acceptance. Prices would go higher, and the amount in the world would remain wholly inadequate.
Raw Bone.—Stable manure lasts several years in the soil because decay is slow. Raw bone has appealed to many because its action is likewise necessarily slow. The fat in it prevents fine grinding and protects the coarse particles from decay. It is known as bone-meal or coarse ground-bone. A good quality of raw bone may contain 4 per cent of nitrogen, while the phosphoric-acid content is 20 to 25 per cent. The bones of old animals is less rich in nitrogen. The age of the animals, and the sorting for manufactures of various kinds, cause variation in quality, and the purchase of raw bone should be made on guaranteed analysis just as surely as the purchase of bone that has been treated in any way for removal of various substances in it.
Steamed Bone.—When animal bone is boiled or steamed under pressure for removal of the fat and the cartilage, the content of nitrogen is reduced, and the percentage of phosphoric acid is increased by this removal of fat and nitrogenous substance. The nitrogen in steamed bone may run as low as 1 per cent, and the phosphoric acid may go up to 30 per cent. The composition of steamed bone is so widely variable that the name means little, and purchase should be made only on guaranteed analysis. Some grades run very low both in nitrogen and phosphoric acid, due probably to adulteration.
The boiling or steaming of bone makes fine grinding possible, and the fineness and absence of fat permit quick decay in the soil. Steamed bone is an excellent source of phosphoric acid. The availability is less immediate than that of acid phosphate, but much greater than that of raw bone.
Rock-phosphate.—While the greater part of our soils contain relatively scant stores of phosphoric acid, the deposits of this plant constituent in combination with lime are immense. The rock now chiefly used in this country is found in South Carolina, Tennessee, and Florida. It varies greatly in content of phosphoric acid. When pulverized for direct use on land, without treatment with sulphuric acid to make the plant-food available, a grade running 28 per cent phosphoric acid, or less, usually is selected, the higher grades being reserved for treatment with acid or for export. This untreated rock, pulverized exceedingly fine, often is known as floats.
The value of a pound of phosphoric acid in floats, as compared with that of a pound in the treated rock, known as acid phosphate, is a matter upon which scientists differ widely. Only a small percentage of the plant-food is immediately available, and the question of wise use hinges upon the degree of availability gained later, and the time required. The large amount of experimental work that has been done affords data that causes the following opinion to be stated here: Rock-phosphate, known as floats, is not a profitable source of plant-food for soils deficient in organic matter, when compared with acid phosphate. It is more nearly profitable in an acid soil than in one that has no lime deficiency. It gives more satisfactory results when mixed intimately with stable manure than when used upon land that remains deficient in organic matter. Applications should be in large amount per acre—500 to 1000 pounds—in order that the amount of readily available phosphoric acid may meet the immediate need of plants. Dependence should be placed upon the readily available acid phosphate in all instances until experiment on the farm shows that the rock-phosphate is a cheaper source of plant-food than the acid phosphate.
Acid Phosphate.—When animal bone is treated with sulphuric acid, the result is an acid phosphate, but treated animal bone is so rare on the market that it may be ignored. The acid phosphate on the market is rock-phosphate treated with sulphuric acid to render its plant-food available. The content of phosphoric acid varies because the original rock-phosphate varies, but the most common grade on the market is guaranteed to contain 14 per cent available phosphoric acid, and 1 to 2 per cent insoluble. Some acid phosphate is guaranteed to contain 16 per cent available phosphoric acid, and some runs down to 10 per cent available.
An acid phosphate contains quickly available plant-food. A prejudice exists against it on account of its source, and it has been a common practice to label the bags "bone-phosphate," or "dissolved bone," or such other designation as would imply an organic source, but the acid phosphate is made out of rock-phosphate, regardless of the name given. The prejudice against the rock as a source of plant-food is giving way. It is our chief and cheapest source of supply. The combination of sulphuric acid with rock-phosphate in the production of acid phosphate produces sulphate of lime, known as gypsum or land-plaster. The amount of gypsum in a ton of acid phosphate varies, but may be roughly estimated by the buyer as two thirds of the total weight of the acid phosphate.
The tendency of gypsum is, in the long run, to make a soil acid, and its use necessarily hastens rather than retards the day when a lime deficiency will occur. The influence in this direction is not great enough to be a very material factor in deciding upon a carrier of phosphoric acid. If a soil has little lime in it, a state of acidity soon will come anyway, and the increase in amount of required lime will be small. The cheapness of acid phosphate, as compared with animal bone, is the decisive factor.
The ill-effects usually attributed to acid phosphate are not due in any great degree directly to the sulphuric acid used in its making, but to the bad farming methods that so often attend its use. When the need of commercial fertilizers is first recognized, acid phosphate seems to meet the need. The soil's store of available phosphoric acid gives out first, and this fertilizer brings a new supply. If the available potash is in scant amount, the acid phosphate helps in this direction by freeing some potash. The phosphoric acid has peculiar ability in giving impetus to the growth of a young plant, and that enables it to send its roots out and obtain more nitrogen than it otherwise would do. The farmer thus may come to regard it as a means of securing a crop, and there is neglect of manure and clover. If a field is thin and fails to make a sod, there is no immediate compulsion to use manure or to grow a catch crop to get organic matter, but the field is cropped again with grain. Soon the supply of humus is exhausted, the soil lies lifeless, and the stores of available nitrogen and potash are in a worse depleted state than formerly.
The fault lies with the method. The phosphoric acid in the acid phosphate was needed. Profit from its use was legitimate, but the necessity of supplying organic matter became even greater than it would have been otherwise. Tens of thousands of our most successful farmers use heavy applications of acid phosphate, but they keep their soils in good physical condition by the use of manure or clover, and they apply potash and nitrogen when needed. The clover is assured by using lime wherever it is in too limited supply, and that is the case in most instances, regardless of the use of any kind of commercial fertilizer.
Basic Slag.—When iron ores contain much phosphorus, its extraction by use of lime gives a by-product in the making of steel that has agricultural value. The ores of the United States usually do not give a slag sufficiently rich in phosphorus to be valuable. Nearly all the basic slag used as a fertilizer is imported from Germany, and usually contains 17 to 18 per cent of phosphoric acid. The availability of the plant-food in this fertilizer has been the subject of much discussion. The chemist's test which is fair for acid phosphate is admittedly not fair when used for basic slag. Field tests, at experiment stations and on farms, are our best sources of knowledge. When the soil is slightly acid, each 1 per cent of phosphoric acid in the slag appears to be about as valuable as each 1 per cent of the available phosphoric acid in an acid phosphate. Some of the effectiveness may be due to the lime, although very little of it is in forms regarded as valuable for the correction of soil acidity. There is evidence that basic slag favors clover. It has not been found feasible to ship this material many hundreds of miles inland from the seaboard to compete with acid phosphate, but it is an excellent source of phosphoric acid for soils that are not rich in lime.
Muriate of Potash.—The mines of Stassfurt, Germany, contain an inexhaustible supply of potash in various compounds. Muriate of potash is prepared from the crude salts, and the commercial product on our markets has the appearance of a coarse and discolored salt. It is handled in large bags, and inclines to become moist by absorption of water from the air. It contains some common salt. The content of actual potash is about 50 per cent. The potash is readily available, but the loss from leaching out of the soil is very small. Muriate of potash is our cheapest source of potash, and should be used for all staple crops except tobacco, sugar beets, and, possibly, the potato. Tests even on heavy soils fail to show any injury to the quality of the potato, and on light soil the muriate may always be used.
Sulphate of Potash.—Some sulphate of potash is imported into this country. Its content of potash may vary 1 or 2 per cent below or above 50. Its physical condition favors mixing more than does the muriate. It usually costs several dollars a ton more than the muriate, and the fact that it is known to favor quality in tobacco, and is popularly supposed to do so in the potato, creates demand at the higher price. It is soluble in water, and quickly available. As a rule, it has no higher agricultural value than the muriate.
Kainit.—Unlike muriate and sulphate of potash, kainit is a crude product of the German mines, having received no treatment to remove impurities. It contains 12 to 13 per cent of potash, and is rated as a sulphate, but one third of it is common salt, and in effect upon quality it should be classed with muriate and not sulphate. Its low content of plant-food should confine its use to regions relatively near the seaboard. When shipped far inland, the price becomes too high to give a reasonably cheap pound of potash.
Wood-ashes.—Wood-ashes contain lime and potash, with a small percentage of phosphoric acid. The market price is above agricultural value, and any needed potash should be obtained from the German potash salts.
Other Fertilizers.—Manufacturers of commercial fertilizer make use of other materials, some of which, like manufactured nitrogen, are excellent, and others are low in quality and slow in action. The sources of plant-food that have been described form the great bulk of all fertilizers on the market, and from them may be selected all the materials a farmer needs to use on his land, either singly or home-mixed. In most instances the selection will embrace only four or five of these fertilizing materials.
Salt.—Salt is not a direct fertilizer, and its use is not to be advised unless it can be secured at a very low price per ton. Some soils have been made more productive by the application of 200 to 300 pounds per acre, and chiefly in case the salt was mixed well with the soil when the seed-bed was made. The practice of using salt as a top-dressing on wheat in the spring gives less effectiveness it is believed. Salt frees potash in the soil, and may have some practical effect upon soil moisture. As a soil amendment, salt has had more reputation than its performance justifies. If land is infertile, it is better, as a rule, to apply actual plant-food.
Coal-ashes.—There is no plant-food of value in coal-ashes. The physical condition of heavy soils is improved by an application, and their use may be quite profitable in this way if cost of application is small. When used as a mulch, ashes conserve moisture.
Muck.—The use of muck pays in stables, as it is a good absorbent and contains some nitrogen which gains in availability by mixture with manure. Its direct application to land as a fertilizer does not pay the labor bill under ordinary circumstances.
Sawdust.—As a fertilizer, sawdust does not have much value, but serves as an excellent absorbent in stables. Its presence in manure need not cause fear of injury to the soil. When fresh sawdust is applied in large quantity to a sandy soil, the effect upon physical condition is bad, increasing drouthiness.
CHAPTER XVIII
PURCHASING PLANT-FOOD
Necessity of Purchase.—The necessity of buying plant-food in the form of commercial fertilizers is a mooted question in any naturally fertile agricultural region just so long as crop yields do not drop to a serious extent. The natural strength of the land and the skill that enters into the farming are important factors in determining the profitableness of recourse to purchased plant-food. The free use of organic matter to maintain the supply of humus defers the time when commercial fertilizers should be used. Good tillage frees the potential plant-food of the soil, and delays the day of necessary purchase. The farm so situated that it can have all its products fed upon it is longer independent of outside help. The profitable use of feeding-stuffs from other farms is a safe way of escaping the direct purchase of fertilizers, although it is a transfer of fertility to the farm as surely as the employment of fertilizers, and is not a method that may have general adoption.
The organic sources of fertility, such as slaughter-house refuse, are containers of plant-food as surely as is stable manure. The inorganic sources, such as acid phosphate and muriate of potash, are containers of plant-food as surely as is animal bone or blood. There is no line that may be drawn to debar any substance that supplies plant-food profitably and contains no compound harmful to the soil.
The purchase of plant-food should begin whenever profit is offered by it, and in connection with its use there should be good tillage, organic matter, and healthful plant conditions in every respect. The use of a fertilizer pays best when the conditions are such that the plants can avail themselves of it in the fullest degree. Good farming and the heavy use of commercial fertilizers go consistently hand-in-hand.
Fertilizer Control.—The dreams of the patent-medicine vender never pictured more favoring conditions for his activity than were found by fertilizer manufacturers and agents before state laws provided for inspection and control. Men who wanted to do a legitimate business welcomed protection from the unscrupulous competition that dishonest men employed. The memory of some of the frauds perpetrated lingers, and causes a questioning to-day that is unnecessary. All fertilizer-control laws afford a good degree of legal protection to the buyer, although in most states they do not demand a clearness and fullness in statements of analyses that would be helpful to many, and they fail to require that sources of plant-food be given. Some fertilizers are sold for more than they are worth, and some are bought for soils and crops that need other kinds of plant-food, but this is due to lack of knowledge on the part of the buyer that he can acquire. The law does its part in the work of protection better than many buyers do their part. It has driven fraudulent brands off the market, compelled carefulness in factory-mixing, and given to the intelligent buyer a knowledge of the kinds and amounts of plant-food in the bag or ton. The sampling is done by disinterested men, and the analyses are made by competent chemists. There need be little distrust of the analysis as printed on the bag, unless a failure of the manufacturer to keep his goods up to the standard has been made public in the state's fertilizer bulletin.
Brand Names.—Notwithstanding all that has been done by the state to acquaint the buying public with the composition of fertilizers, many purchasers are guided in selection by the brand name, and that usually is fanciful in character, no matter whether it be "Farmers' Friend" or "Jones' Potato Fertilizer." In either case it may be far from friendly to soil or pocket-book, and widely at variance with the needs of the soil for which it is purchased. The pretense of making a fertilizer peculiarly adapted to the potato, or to wheat, or to corn would not attract a single buyer if the public would compare the analyses of these special crop fertilizers offered by manufacturers and note their dissimilarity of composition. Any kind of a mixture may be given any kind of a name. It is the composition that counts. The farmer is in the market for nitrogen and phosphoric acid and potash, singly or combined, for a certain soil, and all he wants is to know the number of pounds he is getting, its availability, and its price per pound. Any added detail not required by law is an impertinence.
Statement of Analysis.—It would be well if the law refused to the manufacturer the privilege of printing unnecessary detail in the statement of analysis that must be placed upon the fertilizer bag. It is added to confuse the buyer and mislead him regarding actual value. The following statement is an example of this practice:
ANALYSIS
Per Cent Nitrogen 0.82 to 1.00 Equal to ammonia 1.00 to 2.00 Soluble phosphoric acid 6.00 to 7.00 Reverted 2.00 to 3.00 Available 8.00 to 10.00 Insoluble 1.00 to 2.00 Total 9.00 to 12.00 Potash (actual) 1.00 to 2.00 Equal to sulphate of potash 2.00 to 3.00
As the row of larger figures is not guaranteed percentages, it has no value.
The buyer is not concerned regarding the amount of ammonia to which the nitrogen is equal, and so the second line is a needless repetition.
The fifth line gives the sum of the third and fourth, the available being the total of the soluble and reverted. Therefore the third and fourth lines may be ignored.
The sixth line gives the percentage of unavailable phosphoric acid in the rock, and should be ignored by the purchaser who wants available plant-food.
The seventh gives the sum of the available and insoluble, and should be ignored.
The ninth is a restatement of the eighth line.
There then remains the following guaranty:
Per Cent Nitrogen 0.82 Available phosphoric acid 8.00 Potash 1.00
This is a low-grade fertilizer whose cheap character becomes apparent when the unnecessary statements and restatements are erased. A ton of it contains only 16 pounds of nitrogen, 160 pounds of phosphoric acid, and 20 pounds of potash.
Valuation of Fertilizers.—The manufacturer of a mixed fertilizer must make use of the unmixed materials he finds upon the market. The prices of the various plant constituents in the different unmixed materials can be determined by averaging quotations in leading markets for a given length of time. The fair retail price is obtained by adding about 20 per cent to the wholesale cash price. The retail cash price per pound of the plant constituents in leading markets is thus determined for their various forms and carriers. A pound of nitrogen in dried blood may have its valuation fixed at a figure 50 per cent higher than that of a pound of nitrogen in nitrate of soda simply because the dried blood sells at a price per ton that makes that difference. It is true commercial value that is sought, and that may be very different from agricultural value.
The mixed fertilizer of the manufacturer has its content of plant-food known by analysis. Its number of pounds of the various constituents in a ton is known, and the retail price per pound of these substances has been fixed. The commercial value per ton can then be determined, provided proper allowance is made for cost of mixing and bagging. The individual must pay in addition the freight, and usually a considerable sum for unnecessarily costly methods of distribution and collection.
A Bit of Arithmetic.—This paragraph is intended to serve the man who is willing to be reasonably near right if he cannot be wholly so: A ton is 2000 pounds, and one per cent is 20 pounds. In dealing with fertilizers it is the practice to call 20 pounds, or one per cent of a ton, a unit, and to base the price of the nitrogen, and phosphoric acid, and potash, on the unit. This is done for convenience. If five cents is a fair price for a pound of available phosphoric acid in one's locality, as it would be if a ton of 14 per cent acid phosphate cost $14, a unit of 20 pounds is worth $1. Each one per cent guaranteed is thus worth a dollar, and the phosphoric acid in the fertilizer is easily valued. If a pound of potash in a ton of muriate is worth five cents in one's locality, as it would be if a ton of muriate cost $50, the muriate being one half actual potash, a unit of 20 pounds of potash is worth $1. Each one per cent of guaranteed potash is thus worth one dollar, and the entire content of potash is easily valued. If a pound of nitrogen in nitrate of soda is worth seventeen and one half cents a pound in one's locality, as it would be if a ton of nitrate of soda cost $54, a unit, or one per cent, is worth $3.50, and the content of nitrogen is easily valued.
The prices named would seem high to good cash buyers near the seaboard, and they are too low for some other regions where freights are very high. They are only illustrative. The consumer can get his own basis for an estimate by obtaining the best possible cash quotations from city dealers. Some interested critic may point out that nitrate of soda should not be the sole source of nitrogen in a fertilizer on account of its immediate availability. Manufacturers use some sulphate of ammonia, and a pound of nitrogen in it has had practically the same market price as that in nitrate of soda. Tankage may be used in part, and in it the nitrogen costs very little more per pound.
It may be said that the potash in the fertilizer is in form of sulphate. Usually that profits the user nothing, and often the claim is baseless, but if it is a sulphate, the cost of the potash should have only 20 per cent added to the valuation of the potash, which usually will not add one dollar to the total cost of the ton of mixed fertilizer. Basing the valuations of the pounds of plant-food in the mixed fertilizer on the value per pound in unmixed materials delivered to one's own locality, there must be taken into account the added expense of mixing.
High-grade Fertilizers.—A high-grade fertilizer is not necessarily a high-priced one. What we want in a fertilizer is a high content of the plant-food needed, together with desirable availability. If only phosphoric acid is wanted, a 14 per cent, or 16 per cent, acid phosphate is high-grade because it contains as many pounds of available phosphoric acid in a ton as the public can buy in a large way. A 10 per cent acid phosphate is low-grade. The effort is to escape paying freight, and other cost of handling, on waste material as far as possible. Generally speaking, the higher the percentages of plant-food in a fertilizer, the cheaper per pound is the plant-food. A low-grade fertilizer rarely fails to be an expensive one because the expense of handling adds unduly to the price per pound of the small content of plant-food.
CHAPTER XIX
HOME-MIXING OF FERTILIZERS
The Practice of Home-mixing.—The business of compounding fertilizers has been involved in a great deal of unnecessary mystery. Many of our best station scientists have labored to show that the home-mixing of fertilizers is a simple and profitable piece of work, and the heaviest users of fertilizers in the east now buy unmixed materials, but a majority of farmers use the factory-mixed. Manufacturers are right in their contention that many people do not know what materials are best for their own fields, or what proportions are best, but the purchase of mixed materials does not solve their problem and it does not help them to a solution as quickly as home-mixing. The source of the plant-food in the factory-mixed goods is not known, while it is known in the home-mixed.
Effectiveness of Home-mixing.—Van Slyke says ("Fertilizers and Crops," p. 477): "Manufacturers of fertilizers and their agents have persistently sought to discourage the practice of home-mixing, but their statements cannot be accepted as the evidence of disinterested parties. It has been represented to farmers that peculiar and mysterious virtues are imparted to the plant-food constituents by proper mixing, and that really proper mixing can be accomplished only by means not at the command of farmers. Such statements are misrepresentations, based either upon the ignorance of the person who makes them or upon his determination to sell commercial mixed goods."
Criticisms of Home-mixing.—The manufacturer's advocate formerly laid much stress upon the danger attending the treatment of bones and rock with sulphuric acid. That is a business of itself, and the home-mixer has nothing to do with it. He buys on the market the acidulated bone or rock, just as a manufacturer makes his purchase.
It is claimed that the manufacturer renders a great public service by using supplies of plant-food that the home-mixer would not use, and thus conserves the world's total supply. Let us see the measure of truth in the statement. The manufacturer gets his supply of phosphoric acid from rock, bone, or tankage exactly as does the home-mixer. His potash he buys from the syndicate owning the German beds, and the farmer does the same. These sources must contribute all the phosphoric acid and potash used on land, if we except trifling supplies of ashes, marl, etc., and the only difference in the transaction is that in one case the manufacturer buys the materials and mixes them, and in the other case the farmer buys them direct and mixes them. The remaining constituent is the nitrogen. If the manufacturer uses nitrate of soda, sulphate of ammonia, bones, tankage, or manufactured nitrogen, he does what the home-mixer may do. Most nitrogen must come from these sources. If all came from these sources, the increased demand would not affect the price. The beds of nitrate of soda will last for hundreds of years, the present waste in ammonia from coal is immense, and the supply of manufactured nitrogen can be without limit. The saving in use of inert and low-grade forms of nitrogen is more profitable to the manufacturer than to the farmer who buys and pays freight on low-grade materials.
The rather remarkable argument is advanced that fertilizer manufacturers do not make a large per cent on their investment, despite the perfection of their equipment, and therefore the farmer cannot find it profitable to mix his materials at home. By the same reasoning, assuming for the moment that the profit in manufacturing does not pay a heavy dividend on all the stock issued, if a great hotel does not find its dining-room a source of profit, as many hotels do not, no private home should hope to prepare meals for its own members in competition with hotels.
As has been stated, every user of commercial fertilizer should learn what a pound of plant-food in unmixed material would cost him, selecting the common materials that are the only chief sources. If he can buy a pound of nitrogen in nitrate of soda or sulphate of ammonia, a pound of phosphoric acid in acid phosphate or steamed bone, and a pound of potash in muriate or sulphate of potash for less than they would cost in the factory-mixed goods offered him, allowing to himself a dollar or so a ton for the labor of mixing, it is only good business to buy the unmixed materials. The saving usually is from five to ten dollars a ton, excepting only interest on money, as he would pay cash for the unmixed material.
The cost of bags always is mentioned. That is not to be considered by the farmer, as he uses the bags in which the unmixed materials come to him.
The Filler.—There has been much misleading use of the word "filler," as applied to fertilizers. We have seen that a pure grade of dried blood contains about 13 per cent of nitrogen. The buyer of a ton of dried blood thus gets about 260 pounds of plant-food. The remaining 1740 pounds constitute what may be called nature's "filler." The blood is a good fertilizer. We do not buy nitrogen in a pure state. We buy a ton of material to get the needed 260 pounds of nitrogen. Thus it is with nitrate of soda, sulphate of ammonia, acid phosphate, muriate and sulphate of potash, and all other fertilizer materials. As freight must be paid upon the entire ton, it usually pays best to select materials that run high in percentage of plant-food. It is possible to get very low-grade fertilizers that have not had any foreign material added by the manufacturer. An acid phosphate may be poor in phosphoric acid because low-grade rock was used in its manufacture. Kainit is a low-grade potash because the impurities have not been taken out. Filler may be used, however, for two reasons, and one is legitimate. When limestone or similar material is used merely to add weight, reducing the value per ton, the practice is reprehensible. The extent of this practice is less than many suppose, preference being given to the use of low-grade materials in making very low-priced fertilizers.
A legitimate use of filler is to give good physical condition to a fertilizer. Some materials, such as nitrate of soda and muriate of potash, take up moisture and then become hard. The addition of peat or limestone or other absorbent is necessary to keep the mass in condition for drilling. The use of some steamed animal bone or high-grade tankage in the mixture helps to prevent caking. The home-mixer can use a drier without loss, as he does not pay freight upon it. Dry road dust will serve his purpose. His need of a drier may be greater than that of the manufacturer, as he probably will use only high-grade unmixed materials. If the use of the home-mixture is immediate, no drier to prevent caking is needed, but its presence facilitates drilling. Storage of unmixed materials in a dry place is an aid in maintaining good condition.
Ingredients in the Mixture.—The matters of interest to the farmer are the determination of the amounts of nitrogen, phosphoric acid, and potash that he should apply to a particular field, their availability, and their cost. Let us assume that he has found 300 pounds of a fertilizer containing 3 per cent nitrogen, 10 per cent phosphoric acid, and 6 per cent potash to be an excellent application for wheat on a thin soil that is to be seeded to clover and timothy. This fertilizer contains 3 pounds of nitrogen to each 100 pounds. He applies 300 pounds of the fertilizer per acre, or 9 pounds of nitrogen. The fertilizer contains 10 pounds of phosphoric acid to the 100 pounds. He thus applies 30 pounds of phosphoric acid per acre. The fertilizer contains 6 pounds of potash per 100 pounds, and he therefore applies 18 pounds per acre. What he has really learned, then, is that an acre of this land, when seeded to wheat, needs 9 pounds of nitrogen, 30 pounds of phosphoric acid, and 18 pounds of potash. It is in these terms he should do his thinking, and the matter of fertilization becomes simple.
In the general farming of the Pennsylvania experiment station, it is the practice to depend upon nitrate of soda as the source of a fertilizer for wheat. Manufacturers claim that sulphate of ammonia and tankage would be better. The farmer soon will learn what he prefers for his soil, provided he practices home-mixing.
Let us assume that he uses nitrate of soda, which never varies much from 15 per cent in its content of nitrogen. If 100 pounds of nitrate contain 15 pounds of nitrogen, the 9 pounds wanted for an acre will be found in 9/15 of 100 pounds or 60 pounds.
Thirty pounds of phosphoric acid are wanted for an acre. If the acid phosphate contains 14 per cent of phosphoric acid, or 14 pounds to the 100, the required amount will be 30/14 of 100, or 214 pounds.
Eighteen pounds of potash are wanted for an acre. The muriate of potash on our markets never varies much from 50 per cent in its content of potash. If 100 pounds of muriate contain 50 pounds of potash to the 100, the required amount wanted will be 18/50 of 100, or 36 pounds.
Adding the 60, 214, and 36 pounds, we have 310 pounds for the acre of land. If the field contains 20 acres, the order will call for 20 times the 60 pounds of nitrate of soda, 20 times the 214 pounds of acid phosphate, and 20 times the 36 pounds of potash.
If the farmer prefers to use sulphate of ammonia, which varies little from 20 per cent of nitrogen, or 20 pounds in the 100, he will get his 9 pounds of nitrogen for an acre by buying 9/20 of 100 pounds, or 45 pounds, and the substitution of the 45 pounds of sulphate of ammonia for the 60 pounds of nitrate of soda will reduce the total application of fertilizer per acre from 310 pounds to 295 pounds. The important fact is that in either case there is the required amount of nitrogen.
Let us assume that the field contains enough nitrogen, but other needs remain the same. In such case, the nitrogen is dropped out, and the application becomes 250 pounds per acre.
The home-mixer may substitute tankage of guaranteed analysis for part of the nitrogen and phosphoric acid. Let us assume that the tankage runs 9 per cent nitrogen and 20 per cent phosphoric acid. If half the required nitrogen per acre, or 4-1/2 pounds, is wanted in tankage, 50 pounds of the tankage will supply it. At the same time the 50 pounds of tankage supplies 10 pounds of phosphoric acid, replacing one third of the 214 pounds of acid phosphate. We thus have for the acre 30 pounds of nitrate of soda, 50 pounds of tankage, 143 pounds of acid phosphate, and 36 pounds of potash, or 259 pounds. The content of plant-food remains the same, but one half of the nitrogen is only slowly available. The farmer who buys unmixed materials will incline to use only a few kinds, and at first he will confine himself chiefly to materials whose composition varies little. In this way he quickly sees in a ton of the material, not the whole bulk, but the definite number of pounds of nitrogen and other constituents of plant-food contained in it, and the calculations in home-mixing become simple.
Materials that should not be Combined.—The advocate of factory-mixed goods warns the farmer against the danger of making combinations of materials that will cause loss by chemical action. The danger is wholly imaginary if no form of lime, wood-ashes, or basic slag is used in the home-mixtures. As has been said, some materials will harden, if permitted to absorb moisture, and if the mixture must stand, a few hundred pounds of muck or dry road dust should be added to each ton as a drier, and a correspondingly larger amount per acre should be applied.
Making a Good Mixture.—The process of mixing is simple, and careful station tests have shown that it is fully as effective as factory-mixing. The unmixed materials should be kept in a dry place until the mixing is done. If there are any coarse lumps, a wooden tamper can crush them on the barn floor, and the material should be passed through a sand-screen. The material of largest bulk should be spread on the floor, and the other materials should be put on in layers. Three careful turnings with a shovel will secure good mixing. Scales should be used to secure accuracy in desired amounts of the materials.
Buying Unmixed Materials.—Acid phosphate, animal bone, and tankage can be bought of any fertilizer agent, but when one pays cash, he does well to get quotations from various leading manufacturers. The names of dealers in nitrate of soda can be secured from the New York agency which keeps its address before the public in agricultural papers. This is likewise true in the case of the syndicate controlling all the potash. When the addresses of leading distributors of all needed materials have been secured, quotations should be obtained on a cash basis. The best terms are obtained by groups of men combining their orders.
CHAPTER XX
MIXTURES FOR CROPS
Composition of Plant not a Guide.—It has been pointed out that a chemical analysis of a soil is not a dependable guide in the selection of a fertilizer. Years ago the theory was advanced that the analysis of the crops desired should be a guide, but it has proved nearly worthless. This theory does not take into account the soil's supply of plant-food. Moreover, a certain crop may demand a large supply of an element at a time of the year when the soil's supply is inactive. The need of nitrogen for grass in the early spring, before nitrification in the soil is active, is an illustration. Let the causes be what they may, the fertilizer formulas that call for plant-food in a fertilizer in the same proportions that it is found in plants are disappointing in their results. The analysis of the plant is not a dependable index.
The Multiplication of Formulas.—Fertilizer manufacturers have made all possible combinations of fertilizer materials, using them in various quantities. Each manufacturer has given a mixture a brand of his own, and confusion reigns. There is no formula for a soil or crop that will remain absolutely the best, even for one particular field. It represents one's judgment of the present need, and is employed subject to change, just as is the prescription of a physician. It is usually only an approach toward the most profitable amount and kind of plant-food that may be supplied. The one important consideration is that no manufacturer can know the need nearly so well as the intelligent farmer who knows the history of his field and constantly tests its ability.
A Few Combinations are Safest.—It is the best judgment of scientists to-day that greater results would be obtained from the use of commercial fertilizers if the number of formulas could be reduced to ten, or even a less number. The satisfactory fertilizers fall into three classes:
1. The phosphatic fertilizer, carrying phosphoric acid to land that gets its nitrogen from clover or stable manure, and that continues to supply its own potash. Such a fertilizer should have a high content of phosphoric acid in order that the freight charge, per pound of plant-food, may be as low as possible. Acid phosphate, basic slag, and bone are chief in this group.
2. The combination of phosphoric acid and potash that is needed by soils obtaining all required nitrogen from clover or manure. In most instances the phosphoric acid should run higher than the potash, but the percentage of potash should never run lower than 4. A lower percentage of potash is not as profitable as a higher one, provided any potash is needed. The potash content should be greater than that of the phosphoric acid in case of some sandy soils and of some crops of heavy leaf growth, including various garden crops.
3. The so-called "complete" fertilizer that supplies some nitrogen with the two other plant-constituents. Such fertilizer should furnish, with few exceptions, 3 per cent of nitrogen, if no more.
Amount of Application.—In common practice fertilizers are not applied freely enough when they are used at all. The exception to this rule may be found in the case of small applications to cold and inert soils to force growth in the first few weeks of a plant's life. It is difficult to see how 80 or 100 pounds of fertilizer can affect an acre of land one way or the other, but experience teaches that such an amount can do so in respect to young plants. Phosphoric acid has peculiar power in forcing some development of roots in a small plant, and a small application in the drill or row may help the plants to gain ability to forage for themselves.
In early spring a small application of nitrate of soda has marked effect, tiding the plants over a period of need until the soil is ready to give up a part of its store.
If a soil is not fertile, and fertilizers are needed as an important source of plant-food throughout the season, the application should be liberal. If it is necessary to plant a field that is deficient in fertility, expending labor and money for tillage and seed, the only rational course is to furnish all needed plant-food for a good yield. There may be little net profit from the one crop, but there will be more than could be obtained without the liberal fertilization, and the soil will be better equipped for another crop. This applies, in a notable degree, to fertilization of a wheat crop with which timothy and clover will be seeded. The difference in cost of 350 pounds of a high-grade fertilizer and 150 pounds of a low-grade one, when applied to a poor soil under these circumstances, may be recovered in the grain crop, and at the same time a good sod will be made possible for the permanent improvement of the land. It is a safe business rule that land should be left uncultivated unless enough plant-food can be provided in some way for a good yield. The man who cannot incur a heavy fertilizer bill, when necessary, should restrict acreage for his own sake.
Similarity of Requirements.—Many of our staple crops are very similar in their fertilizer requirements, and this simplifies fertilization. Setting aside the impression gained from the dissimilarity in the so-called corn, potato, wheat, and grass fertilizers on the market, the farmer knows that the soil which is in a good state of fertility is best for any of them, and if the soil is hard-run, it should have its plant-food supply supplemented. The hard-run soil usually is lacking in available supplies of all three plant-food constituents. If a fertilizer containing 3 per cent of nitrogen, 10 per cent of phosphoric acid, and 6 per cent of potash serves the wheat well, it will serve the timothy that starts in the wheat. Likewise it will serve the corn, although a heavier application will be needed because corn is a heavy feeder. Experience has taught that it will serve the potato similarly, and that the potato will repay the cost of free use of fertilizer. If the soil is sandy and deficient in potash, the percentage of phosphoric acid may be cut to 8, and the percentage of potash raised to 10, and all these crops will profit thereby. If the nitrogen content in the soil is high, none of these crops may need nitrogen in the fertilizer. This is a general principle, and safe for guidance, though the best profit will demand some modification that readily occurs to the farmer as he studies his crops and their rotation. To illustrate: The corn is given the clover sod or the manure partly because it requires more plant-food than the wheat. It gets the best of the nitrogen, and may need only a rock-and-potash fertilizer, while the wheat that follows may need some available nitrogen to force growth in the fall. There is no fixed formula for any field or crop, and the point to be made here only is that the requirements of many standard crops do not have the dissimilarity usually supposed, except in respect to quantity. A marked exception is found in the oat crop, which does not bear the application of much nitrogen, and often fares well on the remains of the manure that fed the corn, if some phosphoric acid is added.
Maintaining Fertility.—A heavy clover sod gives assurance that a good crop of corn or potatoes can be grown. If the amount of plant-food in the sod is not excessive, a heavy crop of wheat can be produced. The condition of the soil favors many crops. The clover has placed it upon a productive basis for the time being.
The object that should be kept in view, when a scheme of soil fertilization is worked out, is the maintenance of such a state of fertility that the land can be depended upon for whatever crop comes round in the rotation. When a 3-10-6 fertilizer, or a 3-8-10 fertilizer, is used, the effect upon a thin soil is to restore it temporarily to this good-cropping power, the size of the application varying with the crop. A richer soil may want the phosphoric acid and potash without the nitrogen. A manured soil may need only the phosphoric acid. The purpose of the fertilizer in any case is maintenance or increase of fertility, and when this object has been secured, the crop may be whatever the rotation calls for. It is this rational scheme that gives success to the Pennsylvania station's methods on some of its test plats. A given amount of plant-food is put upon the land, which is under a four-years' rotation. One half of it is applied every second year. The corn gets one half because it can use it to advantage. The oat crop that follows finds enough fertility because the soil is good. Next in the rotation is the wheat, and the wheat and timothy and clover plants can use fertilizer with profit. There is no change in its character because it is the soil that is getting the assistance, and not primarily just one crop in a rotation. The land in this experiment that is well fertilized is more productive than it was thirty years ago, although no manure has been applied, and it is the general productive condition that assures good yields, and not chiefly any one application of fertilizer.
Fertilizer for Grass.—A fertile soil will make a good sod. A thinner soil should have a liberal dressing of complete fertilizer at seeding time, and the formula that has been suggested is excellent for this purpose. If a succession of timothy hay crops is desired, the problem of maintaining fertility is wholly changed. The nitrogen supplied by the clover is soon exhausted, and the timothy sod must be kept thick and heavy until broken, or the soil will not have its supply of organic matter maintained. Nitrogen must be supplied freely, and phosphoric acid and potash must likewise be given the soil. The draft upon the soil is heavy, and at the same time the effort should be to have a sod to be broken for corn that will produce a big crop without the use of any fertilizer. The grass is the natural crop to receive the plant-food because its roots fill the ground, and the corn should get its food from the rotting sod, when broken. Station tests have shown that a sod can be caused to increase in productiveness for several years by means of annual applications of the right combinations of plant-food in the early spring. A mixture of 150 pounds of nitrate of soda, 150 pounds of acid phosphate, and 50 pounds of muriate of potash is excellent. This gives nearly the same quantity each of nitrogen, phosphoric acid, and potash, and is near a 7-7-7 fertilizer. The only material change in relative amounts of plant-food constituents, when compared with a 3-10-6 and 3-8-10 fertilizer, is in the increase of nitrogen, due to the heavy drafts made by continuous mowings of timothy. This fertilizer should be used as soon as any green appears in the grass field in the spring after the year of clover harvest. The large amount of nitrogen makes this an unprofitable fertilizer for clover, and its use is not advised until the spring of the year in which timothy will be harvested.
All the Nitrogen from Clover.—The Pennsylvania station has shown in a test of thirty years that when good clover is grown in a four-years' rotation of corn, oats, wheat, and clover, the fertility of the naturally good clay loam soil may be maintained, and even slightly increased, without the use of any manure or purchased nitrogen. Phosphoric acid and potash have been applied, and the clover hay crop has been taken off the land. This result has been possible only by means of good clover sods. If there had been no applications of phosphoric acid and potash, the clover would have failed to maintain fertility, as is proved by other plats in this experiment. No one should continue to depend upon such a scheme of keeping land fertile whenever he finds that the clover is not thriving.
Method of applying Fertilizers.—If a fertilizer is used in small amount with the purpose of merely giving the plants a start, it should be near the seed. If the application is heavy, and the roots of the plants spread upon all sides, the fertilizer, as a rule, should be applied to all the ground, and should be mixed with the surface soil. This puts the plant-food where needed, and saves from danger of injury to the seed through contact. A seeming exception may be found in the case of the potato, but usually some close tillage confines its roots to the row for a time. Experience indicates that when a potato fertilizer does not exceed 500 pounds per acre, it may well be put into the row, but a heavier application should be divided, one half being broadcasted or drilled into the surface, and the other half of the application being made in the row.
An Excess of Nitrogen.—Too much nitrogen, due to heavy manuring or other cause, produces an excessive growth of stalk or straw, at the expense of grain production, in the case of corn, wheat, and other cereals. It produces a rank growth of potato vines and partial failure of the crop of tubers. It produces a tender growth of straw or vine that invites injury from fungous diseases. It is the rule that soils have a deficiency in nitrogen, but when there is an excess, the best cure comes through use of such crops as timothy, cabbage, and ensilage corn. Heavy applications of rock-and-potash fertilizers assist in recovery of right conditions, but are not wholly effective until exhaustive crops have removed some of the nitrogen.
CHAPTER XXI
TILLAGE
Desirable Physical Condition of the Soil.—Successful cropping of land is dependent upon favoring soil conditions. The plants to be grown must have ease in root extension, so that their food may be found. There must be moisture to hold the food in solution. There must be air. There must be destruction of plants that would be competitors of the ones desired. A soil rarely is in prime condition for the planting and growth of any crop without some change in its structure by means of tillage, and it does not remain in the best condition for any long period of time. If the number of plants required per acre for a crop is relatively small, tillage of the soil is continued after planting. If the necessary number makes tillage impossible, there is some loss in conditions most favorable to the plant. The particles of soil settle together, and there is loss of water at the surface. Most plants want a mellow soil, and tillage is in large part an effort to make and to keep the condition of the soil friendly to plant life in this respect. The wide variation in methods of tillage are due to the great differences in the texture and structure of soils, and to the habits of plants, and skill in selection of methods is a measure of the intelligence used in farming.
The Breaking-plow.—Land containing enough clay to give it an excellent soil inclines to become firm. During the growth of a crop, when plant roots fill the soil and prevent deep stirring, the particles pack closely together, limiting the power of the land to make fertility available. The presence of organic matter counteracts, in part, this packing tendency, but there are few soils that remain permanently mellow. The breaking-plow is used to loosen the soil, and to undo the firming that has been taking place while plant roots prevented deep tillage. At the same time the plow may be used to bury organic matter below the surface, affording a clean seed-bed. In some soils it has value in bringing inert soil to the surface, and in mixing the soil constituents.
Types of Plows.—The kind and condition of the soil, and the character of the crop, determine the type of plow to be used. A plow with a short and quite straight moldboard does not bury manure and turf in the bottom of the furrow so completely as is the case with a long, curved moldboard. The organic matter should be distributed throughout all the soil. On the other hand, it is essential to some plants that they have a fine seed-bed, and one whose surface is free from tufts of grass. The long moldboard is preferred in breaking a sod for corn. Its use in plowing for all crops is more general than it should be, the gain in pulverization of the furrow-slice, due to the curve, and the neatness in appearance of the plowed land, inducing its use.
The disk plow has been used chiefly in soils not requiring deep plowing. It pulverizes better than a moldboard plow, and buries trash more easily.
The device for using two disks to turn a single furrow-slice rests upon a sound principle. This plow may be set to run deeper than moldboard plows go, and it mixes well all the soil that it turns. The disks are so hung that the mixing of all the soil to a depth of twelve or fifteen inches is admirable. The deep-tilling plow does not bury the organic matter in the bottom of the furrow, and thereby permits the deepening of the soil without bringing an undue amount of subsoil to the surface.
Subsoiling.—The theory of subsoiling always has been captivating. Most soils are too shallow, inviting injury from drouth. Enthusiasm regarding subsoiling comes to large numbers of farmers at some time in their experience, and a great number of subsoil plows have been bought. The check to enthusiasm is the fact that few men ever have seen such a plow worn out. Some reasons are as follow:
(a) The subsoil at time of spring-plowing rarely is dry enough for good results, and there is danger of puddling; (b) the subsoil often is too dry and hard in late summer, when rains permit easy breaking of the top soil for fall grain; (c) the work doubles the labor and time of plowing, and (d) the subsoil soon settles together because it contains little organic matter. Subsoiling is generally approved and little practiced. Land at plow-depth becomes packed by the tramping of horses upon it and the pressure of the plow, when the plowing is done at the same depth year after year, and in some soils subsoiling has been found distinctly valuable.
Time of Plowing.—In great measure the time of plowing is determined by the effect upon soil moisture, and is discussed in the next chapter.
Method of Plowing.—The depth of plowing should be fixed largely by the amount of organic matter in the soil. It is essential that a good percentage of this material should be mixed throughout the soil, and when it is in scant supply, the depth of plowing usually should not be great. Fertile soils should be plowed deep for their own good, and thin soils should be deepened gradually, as sods and manures afford a supply of humus-making material. Even when manure is used liberally in a single application on a poor soil, a large amount of inert subsoil should not be thrown upon the surface. The manure goes out of reach of the greatest need, which is in the surface soil where plant-life starts. A gradual process of deepening the soil is to be preferred, but such deepening should not be neglected. The subsoil is a store of inert fertility that should not remain dormant.
It may not do to say that the success of the best farmers is due to thoroughness in plowing, but it is true that the more successful ones are insistent that the plowing be absolutely thorough. Every inch of the soil should be stirred to a certain depth, and that requires a plow so set that it does not turn a furrow-slice much wider than the point can cut. Evenness in depth and width of furrow is seen in good plowing.
The Disk Harrow.—The purpose of the plow is to break up the soil so that it will be crumbly and mellow. The frequency with which land should be thoroughly stirred to full plow-depth depends upon the condition of the soil and the character of the crops. Oftentimes a disk or cutaway harrow may replace the plow. Its action is the same as that of the plow, loosening and turning the soil over. When land has had a good plowing within the year, and has not become compact, stirring to a depth of four inches may give a better seed-bed for some crops than could be made by use of a plow. This is true of land that has produced a cultivated crop and is being prepared for a fall-seeding. The gain in time of preparing ground for oats in the spring makes the use of the disk or cutaway harrow profitable on mellow corn-stubble land.
There is temptation to carry the substitution of the disk harrow for the breaking-plow too far. Its use alone would have the same effect as poor plowing, reducing the depth of the soil. The surface soil, down to plow-depth, is the chief feeding-ground for plants because it is kept in good tilth by organic matter and tillage. The depth of this soil affects the amount of available plant-food and water. The duration of time between deep plowings depends upon the soil and the crops. Experience shows that when land has been broken for corn or potatoes or beans or similar crop, the one plowing may be sufficient for a succeeding crop. If grass is not seeded with the succeeding crop, it is best to give another thorough plowing before seeding to grass in August if the soil is heavy, but in naturally loose soils a disk harrow makes a better seed-bed.
Two influences favor such undue dependence upon a disk harrow that a soil may become shallow: the cost of preparing the seed-bed is reduced, and the saving in moisture may give a better stand of plants when the harrow takes the place of the plow. The immediate productiveness of a crop is not an assurance that the method is right: consideration for the good of the land must be shown. Depth of soil is a requirement of a good agriculture, and deep plowing is a means to that end. The looseness of the soil and the character of the season may make substitution right in one instance and wrong in another. Deep soils, well filled with organic matter, will bear shallow preparation of a seed-bed more frequently than thin soils, and yet it is the latter that may profit most by having its best part kept near the surface at the time a new sod must be made. The disk harrow has some place as a substitute for a plow, but when its use results in making a soil more shallow, the harm is a most serious one.
Cultivation of Plants.—If a soil would remain mellow throughout the season, there usually would be no reason to disturb the roots of plants by any deep stirring, and all tillage would be only deep enough to make a mulch of earth for the retention of moisture and to destroy all weeds. Soils containing enough clay to make them retentive of moisture become too compact when rains beat upon the ground, as usually happens after the planting of spring crops. A deep and close cultivation of corn and potato plants after they appear in the row helps to restore the condition created by the plow and harrow, and often is the best practice. There is some sacrifice of roots, but the gain far exceeds the loss. It may be necessary to give a second such cultivation when a clay soil is deficient in organic matter, but the root-pruning is a handicap.
Controlling Root-growth.—The exception to the rule that plant-roots should not be pruned by deep cultivation is found in the case of a close soil in a wet season. The plants extend their roots only in the soil at the surface because the ground is soaked with water nearly all the time. They cannot form far enough below the surface to withstand a drouth that may follow the wet weather. Good tillage in such a case demands the pruning of the roots and the airing of the soil when the ground is dry enough to permit such stirring, and the plants then extend their roots in the lower soil where they rightly belong. Judgment is required to decide when such tillage is desirable, but judgment is needed all the time in farming. When a continued period of wet weather affects the position of the plant-roots, it rarely is advisable not to risk deeper tillage than is given in a normal season. Underdrainage helps to prevent such ill-effect of continued rains in the early part of a plant's life-time.
Elimination of Competition.—Weeds pump the water out of the soil, use up available plant-food, and compete for the sunlight. Tillage is given for several reasons, and one is the destruction of weeds. A weeder which stirs the soil only an inch or two deep is an excellent destroyer of weeds when they are starting, but after the weeds are well-rooted, the weeder acts only as a cultivator for the plants that should be destroyed. Modern cultivators have fine teeth that let the surface remain nearly level, and they do their best work when the weeds are small. The use of "sweeps" should be more general. The blades are so placed that they slip under the surface, letting the soil fall back so that a mulch is formed.
Length of Cultivation.—Most tilled crops grow rapidly until they shade and mulch the soil. Tillage should continue, if possible, until this occurs. The exception is in the case of orchard trees and other plants that should not have their period of growth extended late in the fall. Good tillage tends to increase the lateness of a crop by encouraging growth. The new wood of trees may not become hardy enough to withstand the frost of winter if tillage is continued. Early maturity is hastened by exhaustion of soil moisture and plant-food.
CHAPTER XXII
CONTROL OF SOIL MOISTURE
Value of Water in the Soil.—The amount of water in the soil each day of the growing season determines in large measure the possibility of securing a profitable crop from land. Observant farmers have noticed oftentimes that the differences in yields on the farms of a region are less in a wholly favorable season than in one of deficient rainfall. The skill of the farmer in conserving the moisture supply in a wet season is less well repaid because it is less needed. The poverty of a worn soil is less marked in a favorable season. The land is accounted poor because the supply of plant-food is inadequate for a drouthy year in which a considerable percentage of the time produces little growth, but most agricultural land has enough plant-food for a fairly good crop when water is present all the time to carry daily supplies into the roots. It is the amount of moisture in the soil that is the limiting factor in the case of most land that is not in a high state of productiveness. |
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